Abstract: The invention relates to polyoxymethylene fibrids with a reduced specific viscosity of 0.4 to 2.0 dl/g, a specific surface area of 50 to 200 m.sup.2 /g and a freeness of 30.degree. to 80.degree. SR. The fibrids are produced by flash-evaporation of a superheated solution of the polymer, a mixture of 50-95% by weight of a lower alcohol with 1-4 C atoms and 5-50% by weight of water being used as the solvent and are suitable for the production of paper.

Abstract: Fiber-containing polyurethane foams having improved compression properties, especially at deformations of greater than 50%, are obtained by incorporating in the foam-forming composition from 0.1 to 10% by weight, based on the weight of finished foam, of polyolefin fibers, e.g., polyethylene or polypropylene fibers, that have been treated to provide them with functional groups that are reactive with isocyanates. The reactive fibers may be obtained by fixing to the fiber surface or incorporating in the fiber polyfunctional compounds, e.g., starch, methylcellulose, carboxy methylcellulose, saccharin, polyglycols, polyvinyl alcohol, hydroxyl-group-containing block copolymers, completely saponified copolymers of ethylene and vinylacetate and oxidation products of a polyolefin.

Abstract: Hydrophilic polyolefin fibers containing more than 50% by weight of clay are obtained by passing a mixture, which is kept under pressure and consists of a polyolefin, a solvent for the said polyolefin, clay, a hydrophilization agent, water and an amine, through a nozzle into a zone of low pressure. The fibers obtained can be used, with small expenditure for working up, for the manufacture of synthetic paper.

Abstract: Hydrophilic polyolefin fibers containing more than 50 weight % of basic pigment, are obtained if a mixture of polyolefin, a solvent for this polyolefin, a basic pigment, a hydrophilization agent, water and an organic acid flows from a pressure vessel through a nozzle into a low-pressure chamber. The thus obtained fibers may be used for preparing synthetic paper without requiring much expenditure for work-up.

Abstract: Hydrophilic polyolefin fibers containing inorganic pigments are obtained by means of flash evaporation of a superheated suspension, which is under at least autogenous pressure. The suspension comprises a dispersion of a hydrophobized inorganic pigment in an emulsion prepared from a solution of a polyolefin in an easily boiling solvent and an aqueous solution of a hydrophilizing agent. The suspension is passed through a nozzle into a low pressure zone to form pigmented fibers.